Circuit breaker movable contact



March 16, 1948. w. M. SCOTT, JR

CIRCUIT BREAKER-MOVABLE CONTACT 4 Sheets-Sheet 1 Original Filed June' '10, 1940 mmw 11-1 lllmfll,

uum ummn MIIIIIIIIIIIIII March 16, 1948. w. M. SCOTT, JR

CIRCUIT BREAKER-MOVABLE CONTACT Original Fi led June 10, 1940 4 SheetsSheet 2 m M W W .1 12M. a 4 a n 0 W 5 m m %M w w w w J V J M v .1 y w T a 5/ f W a W 2 n; 1. w M E; n 2 m... m w M Q llull, Q 5 a: 1 8 F 1 c a w I g m im o m .0 w w m w o Q a m a 7 m? S M 1.1 rm A m m? ATTORNEY INVENTOR,

4 Sheets-Sheet 3 Original Fild June 10, 1940 March 16, 1948.

A TTORN E Y March 16, 1948. w. M. SCOTT, JR 2,437,863

CIRCUIT BREAKER-MOVABLE CONTACT Original Filed June 10, 1940 4 Sheets-Sheet 4 ATTORNEY Patented Mar. 16, 1948 UNITED STATES PATENT OFFICE CIRCUIT BREAKER MOVABLE CONTACT William Maxwell Scott, Jr., Bryn Mawr, Pa., as-

signor to I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania 2 Claims. 1

This invention relates to circuit breakers and switch gear and more particularly to movable contact apparatus therefor. This application is a division of my application Serial No. 339,689 filed June 10, 1940, now Patent No. 2,375,328, issued May 8, 1945.

In the operation and use of circuit breakers and switch gear of various types, it often becomes important to disassemble the same or at least to remove parts thereof in order to obtain access to various portions of the circuit breaker for replacement or repair. I have in the present invention arranged each of the parts so that they may be readily removable without any complicated operations whatever.

An important object, therefore, of the present invention is the arrangement and integration of the parts thereof in such a manner as to facilitate assembly and disassembly thereof in manufacture, operation, replacement and repair.

In the construction of a movable contact of the present circuit breaker, I have provided for contacts which may be supported by a contact carrying arm and which may nevertheless yield to the pressure of the contact supporting arm to a sufiicient degree to permit effective contact pressure to be maintained without destroying the contacts.

For this purpose, I have mounted. the movable contacts upon contact levers which are pivotally supported upon the contact carrying arm and I have provided for various types of biasing means in order to ensure that proper contact pressure will be maintained.

Accordingly, an important object of the present invention is to so arrange the movable contacts that proper contact pressure may be maintained.

Still another important object of the present invention is to so arrange the movable contacts that they may themselves move with respect to the contact carrying arm and thus adjust themselves to proper contact pressure.

A further object of the present invention is likewise to mount the movable arcing contacts upon a similar pivoting lever which in turn is supported by the main movable contact carrying arm.

Still a further important object of the present invention is to so arrange the movable contact and the connections thereto that the passage of current through the contact will itself create magnetic forces which will tend to increase the contact pressure of the movable contact. The type of circuit breaker construction to which my invention relates is more fully shown in Patents Nos. 2,311,690 issued February 23, 1943, to Frank J. Pokorny; 2,348,228 issued May 9, 1944, to William M. Scott, Jr.; 2,311,701 issued February 23, 1943, to William M. Scott, Jr.; 2,338,715 issued January 11, 1944, to Herbert G. Graves, Jr.; 2,375,328 issued May 8, 1945, to William M. Scott, Jr.; and 2,390,735 issued December 11, 1945, to Frank J. Pokorny.

There are many other objects and uses of the present invention and of the combinations and elements herein set forth. Many of them have already been pointed out. Many others will in part be apparent and where not intrinsically apparent will be pointed out in the following description and drawings, in which:

Figure 1 is a side elevation of the circuit breaker of our invention.

Figure 2 is a front view of the circuit breaker arrangement of Figure 1.

Figure 3 is a cross-sectional view of line 3-3 of Figure 2 showing the circuit breaker in closed circiut position.

Figure 4 is a View corresponding to that of Figure 3 showing the circuit breaker in open circuit Position.

Figure 5 is a cross-sectional view on line 5-5 of Figure 4 showing the arrangement of the arc quencher.

Figure 6 is a view of the back of the contact supporting shaft, showing the back of the contact arms.

Figure 7 is a cross-sectional view on line 1-7 of Figure 6.

Figure 8 is a cross-section of the contact assembly on line 8-8 of Figure 7.

Figure 9 is a view in perspective showing the contact surfaces.

Figure 10 is a cross-sectional view on line 10-4 0 of Figure 7.

Referring now to Figures 1, 2, 3 and 4, we have here shown a three pole circuit breaker comprising the elements of the present invention. The circiut breaker consists of a group of pole units 20, 21, 22 (Figure 2) mounted on the face of an ebony, asbestos or slate panel 23 which forms the mounting plate of the entire circuit breaker arrangement.

MAIN SUPPORTING MEMBERS The main bracket or housing 24 which supports the operating members is secured to the panel 23 by means of screws 25, 25 the heads of which are recessed in openings 26, 26 in the back of the panel 23 and which pass through the perforations 21, 21 in said panel to engage the main bracket 25 (Figure 1). 7

As seen in Figures 1 and 2, the main bracket or housing preferably comprises two flanged side plates 28 and 29 which extend on each side of a horizontal shelf 36 to which they are welded. The operating mechanism 3| comprising the toggles and other elements hereinafter described is bolted to the lower side of the shelf 3% the housing 36! of the said operating mechanism comprising flanges 32 (Figures 3 and 4), through which bolts 33 may be passed to engage the shelf 30.

the outer end of the arc chutes in the manner hereinafter described.

MAIN AND Aroma CONTACTS The stationary main contacts The stationary main contacts 38 are bolted to the connecting stud 42 by means of the bolts 33 and the washers 39. The connecting stud 42 passes through the back panel 23 and is suitably arranged so that appropriate circuit connections may be made thereto. The path of the main current when the contacts are closed, as seen in Figure 3, is through the connection stud t2, the stationary contact 36, the stationary contact tip 40, the movable contact tip ii, the contact lever 69 carrying the flexible connection 43 which in turn is electrically connected to the member 44 Movable contacts support The movable contact shaft 45 is preferably a square steel bar covered with phenolic insulation molded in place and is rotatably supported in appropriate bearings as hereinafter described.

A contact arm for each pole is mounted on this shaft. The contact arm dB is preferably a bronze casting reinforced by flanges 51 and 4 .8. The lower end of the bronze casting which engages the square steel shaft is preferably formed in a V comprising the members 49 and set at approximately right angles to each other so that they will engage the square sides of the shaft 45 to which they are to be clamped.

Th clamping member 5| comprises also a V-shaped member having the sides 52 and 53 which likewise may engage the sides of the square steel shaft and comprising also flanges 56 and 55 through which bolts 56 and 5? may be threaded to engage the flange 58 and the flat portion 59 of the contact arm G6 in order to securely clamp the same to the contact shaft 45.

As will be noted, especially in connection with Figures 2 and 3, each of the main contact arms 46 may be secured tothe contact shaft 415 so that rotation of the contact shaft 45 by the lever 35 will result in corresponding movement of the contact arms'dfifor the purpose of opening or closing the circuit.

While any necessary number of contact carrying arms may be mounted upon the contact shaft as the specific circuit connections may require only one lever 35 is necessary for the opening and closing operations which result in rotation of the shaft 55 and the operation of the various contacts.

In order to obtain a balanced structure it is preferred that the lever be secured to the shaft substantially at the center so that the mechanism may be properly balanced.

M doable main contacts Each contact arm 45 carries a pair of contact levers 60 formed and cut from a special copper extruded bar. Each of these two levers 53 (see especially Figures -3 and 4; also see Figure 7) carries at its upper end a silver nickel contact block 4| for engaging the stationary main contact tip 40. The back of the contact arm t5 has a part-cylindrical depression 5i and the front of each of the contact levers has a similar depression 62. A bronze pivot pin 53 is placed in these depressions in the manner shown in Figures 3 and '7. This pivot pin has flanges at each side and also a flange in the center between the two contact levers 60 in order to prevent any lateral movement of the members with respect to each other.

Each of the contact levers 5% is drilled at at so that a pin 65 may be inserted therein. The pin $5 is preferably of dumbbell shape as seen in Figure 10 and acts as an equalizing yoke between the two contacts Bil-5i]. A link 56 engages the pin between the two contact levers til-6t and is extended up through a perforation Si in the contact arm @5 into the recessed area $3 of said contact arm. A compression spring 65 forms the main contact spring and is retained in position between the base of the recess 68 and the spring cup 10 which is held in place on the spring link 66 by the cotter pin 1 l.

The spring link 66 in extendin between the two main contact levers (it has an eye 65' which engages a groove 55' in the pin 95 in order to prevent its moving to either side.

When the main contacts are disengaged in the manner shown in Figure 4, the lower ends E2 of the main contact levers press against the contact arm 56 in the manner shown.

For simplified assembly the only element which retains the pin 63 in place is the pressure of the spring 69 upon the main contact lever.

In the closed position the pressure through the contact lever Eli between the spring t9 (bearing on the pin and the contact it serves to maintain the adequate pressure necessary to hold the pin 63 in place. In the open position, the pressure of the bottom end '12 of the main contact lever 68 against the contact arm 45 and the pull of the compression spring upon the pin 65 of the lever 6i! using the member 72 as a fulcrum serves to maintain the pin 53 in place,

This design of pivot provides long wearing surfaces. The spring link and pressure equalizing pin may be made of hard steel so that their area of engagement may be small. The area of engagement at the pin of the contact levers may be of relatively soft material.

The pivot pin engaged by the half cylindrical surfaces of the contact arm and the contact levers provides a maximum'of area for the softer parts. This area could not be obtained in the same width or pin length .by any other method.

If the levers were formed to rock in a groove in the arm, there would be copper and brass bearing surfaces which are far inferior to the steel stan't when there is any relaxation of pressure upon the pin 63, for until the main moving contact tip M is brought into contact with the stationary contact tip to, the bottom end 72 of the contact lever (it) engages the contact arm 48 in the manner shown in Figure 4.

Only after the moving contact tip f is in engagement with the stationary contact tip to is there a transfer of the fulcrum or the base of pressure from the portion if to the tip ll. In such case, as has been seen in connection with the closed position of Figure 3, there is again sufficient pressure to maintain the pin 53 in place.

During the opening movement, pressure is maintained upon the pin 63 by reason of the fact that spring as by its pressure on pin 65 forces contacts 4i] and il against each other until, in the rotation of the contact shaft t5, the end 12 of the contact lever presses against clamping portion 28 of the contact arm 46, whereupon the base of pressure is transferred from contact tip ii to end portion 72. In this manner, the spring pressure is always exerted to maintain pin 63 in position.

The rotation of the main contact lever 59 about the pin E2 during the closing operation necessarily results in a slight sliding motion of the movable contact tip Z-l with respect to the stationary contact tip it so that a wiping action occurs tending to clean the contacts.

As seen also in Figures 3 and l, the back of the contact levers are drilled and tapped for the securing screws it in order to attach the flexible conductor A3 thereto.

The upper end of the flexible conductor 43 is slit so that separate screws '33 may attach the separate ends to the two separate contact members iii to allow independent movement of the contacts. The arrangement of the lever arms above and below the contact pivot is such that during heavy current flow the magnetic forces set up will tend to increase the pressure between the moving and stationary contacts when the flow of current is between the stationary contact tip and the movable contact tip 4 l.

By the use of two contact levers of this type for each pole of the circuit breaker, an adequate contact at each pole is ensured.

Movable arcing contacts The arcing contacts er are mounted in the upper part of the contact arm 45, and are supported by arcing contact levers E5. The arcing contact levers l5 preferably are each cut from a bar of extruded copper and in this case also I have found it preferable to use a pair of such contacts and levers for a single pole. Each of the arcing contact levers i5 is pivoted on the pin 78 which is grooved between the contacts to take a hair pin spring li which serves to keep the pin it in center position. A second pin 78 is mounted in the top of the contact arm iii between two upwardly extending flanges l9 thereof.

An appropriate bushing may be placed between the flanges so that the pin may be securely riveted over them without bending them. The eye 88 of the spring link Si is placed over the bushing, the said spring link 35 extending beyond the back of the arcing contact levers l5.

Pins 82 having rounded heads (see Figure 8 as well as Figures 3 and 4) are driven into the upper part of the back of the arcing contact lever it.

A spring cup 83 is pressed against these pins by the compression spring 84 which is held in place on the link 8! by the spring cup 85 at the opposite end which in turn is held in position by the cotter pin 86. The arcing contact 87 is mounted upon the arcing contact lever 15 and is preferably formed or cut from an extruded copper bar and is provided with a contact face 88 preferably of Elkonite silver which is soldered to the copper. Each of the contacts 8'! of each of the contact levers 15 is held in place upon its contact lever by a socket head cap screw 89 and lock washer 80. As will be seen more particularly in Figure 9, the contacts 81 are held against turning or other displacements by the shoulder 9i which engages a corner of the arcing contact lever 75. The ends of the contact arm flanges bear against the outer sides of the two arcing contacts and the projection 92 of the spring link separates the two arcing contacts 8'l8l from each other, thus serving adequately to position them.

As is seen in Figures 3, 4 and 9, the lower end of the arcing contact lever is off-set at 93' to receive the end of a flexible conductor 93. The conductor 93 like the conductor 53 is also slit, the ends thereof being riveted at the off-set 93 to the arcing contact lever '55 by means of the rivet es passing through the washer plate 95.

The off-set $3 is curved away at 96 from the flexible conductor and the washer plate is curved away at 97 therefrom for the purpose of preventing kinking during operation. Thi flexible conductor 93 is led down to the lower terminal block 44 to which it is connected by the same screws 98 that held. the main contact lead 43.

The main contact levers 60, in contact open po sition, are held against their fulcrums and against a stop on the arm by a compression spring 69 at the back of the arm, acting on a link 66 connected to the two contact levers between the fulcrum and the stop. The contact surface is at the top of the lever above the fulcrum. The flexible conductor i3 is secured at 73 to the portion of the lever below the fulcrum 63.

When the shaft and arm are moved to contact closed position, the contact ends of the levers are rotated about their fulcrums and pushed back from their advanced position, moving the bottom stop clear of the arm. This compresses the spring and increases the contact pressure. The use of a single spring and link between the two levers permits the pin to act as an equalizing yoke.

The attachment of the flexible conductor below the fulcrum causes the magnetic forces to balance about the fulcrum so that the contact pressure may remain the same or increase during fault current.

The auxiliary or moving arcing contacts are mounted at the top of the arm. In this case the spring is above the fulcrum and below the detachable contact tips. Equalization of pressure is arranged in the same way. Maintained pressure during fault or inrush current is provided in the same manner.

Ovcrcurrent coil connections It should also be noted that the flexible lead Hill from the arcing horn hereinafter described is also connected to the terminal block 44. It will thus be seen that the three flexible conductors I08, 93 and 43 are all led from the contact structure to the lower terminal 44 to which all three are or may be secured by the same screws and lock washers. The angle of the terminal and of the screw 98 is selected so that a repair man '7 may reach ithese'scr'ews over the back edge of the bracket shelf 36.

'Ih'e lower terminal or pigtail posts may have connected thereto a coil H which may energize an over-=current magnet.

This coil may have a cross-section of copper and the requisite number of turns correspondin by means of the bolts IE6 and lock washers I H.

In other words; therefore, the current is not led directly to the back connection stud III but through the lower terminal post A l and through the coil III] of the over current magnet to the back connection stud l l I through which the connection is made to the circuit.

The coil IIfi of the over current magnet is therefore connected in series with the contacts.

It might here be noted that the upper back connection stud 42 is likewise connected through the panel 23 by means of screws H 8 and 9 engaging and passing through the clip 1-28 and is therefore held in position in the same manner as the lower back connection stud I I I.

When the circuit breaker therefore is closed, the current flowing into the upper stud 42 enters the main contact block 35, passes through the main stationary contact surface iii to the main movable contact surface iI and into the main contact lever 66 passing therefrom through the flexible lead E3 to the lower terminal block M around and through the coil Hi] to the lower back connection stud Ill and thence back to the circuit to which the same is connected.

The over-current coil I Ill will thus be in series with the main contact; and, after these are opened, with the arcing contacts; and, finally, with the arcing horns; since the leads 43, 93 and to!) each are connected to the pigtail post as.

The arcing contact circuit is in parallel with the circuit through the main contact tips 40 and SI, The arcing contacts are designed to make before and separate after the main contacts during the closing and opening so .that as is hereinbefore described, the arc particularly during the opening may be made between the arcing contacts so that the main contacts which carry the load should not be roughened or distorted to offer any substantial resistance to the passage of current.

Blow out magnet and stationary arcing contact The current path from the arcing con-tact tip 83 to the arcing contact lever I5 and through the flexible lead 93 to the lower terminal block 44 has been described. The movable arcing contact tip contact tip I21, thence to the movable arcing contact tip '88, thence through the arcing contact 8 lever 15, flexible lead 93, the terminal block M, the coil -I It, and the connection stud H1 in the manner her-einbefore described.

The arcing contacts, particularly the movable arcing tip 83-88, may readily be replaced after the same have become worn, When the circuit breaker is closed, the resistance of the circuit through the main contacts 35 and 6B is low as compared with the resistance through the arcing circuit so that a relatively small current flows through the latter.

The main stationary contact 36 is attached to the back connection stud as is the lower terminal of the blow-out magnet coil 122 by means of screws 33. Screws IE9 passing through panel 23 serve to fasten the lower terminal of blowout magnet coil I22 and angle clip to panel. Screws I 53 in turn fasten back connection stud 42 to the angle clip I26, The electrical connection between the back connection stud 42 and the lower terminal I25 of the blow out magnet coil I22 is made by direct contact between the angle clip I28 and the screw H9 as well as by the direct pressure of the terminal I25 against the connection stud 42.

The coil consists preferably of a strip of bar copper wound in a helix, the lower end at I26 being sweated and pinned by pins I21 and I28 to the lower coil terminal I 25 and the upper end being secured to a flat plate terminal I29 which lies against the panel l2'3. The coil is wound so that current flowing from the lower coil terminal to the upper coil tenminal flows around the slotted cylindrical iron core I36 in a clockwise direction in the views of Figures 3 and 4.

A fiber tube I3I insulates the core 1'30 from the coi1 5'22, Insulated side plates 132 are fastened on each side of the coil terminals. The arcin terminal I23 also cut from an extruded brass bar is secured to the upper coil terminal I29 and the panel 23 by screws "I33, threaded into the nut plate I34 which is further anchored in position to provide a secure attachment of the members by the screws I35, the heads of which are embedded in the recess I36 so that they may not interfere with the securement of the coil terminal I29 to the panel. 7

The upper part I 38 of the arcing contact I23 is extended along the panel and forms a hook I39 for anchoring the arc chute in the manner hereinafter described.

The arcing contact I23 curves around the blow out coil as seen in Figures 3 and 4 and forms an arcing horn. The arcing contact is preferably wider than the coil I 22 and as seen in Figures 3 and 4, its under-surface rests against the edges of the insulating side plates I 32. As has been above described, the arcing contact tip I'2I is at the lower end of the arcing contact 123 and is preferably a contact surface of Elkonite silver.

As seen in Figures 2 and 7, the contact shaft 45 is a square steel bar which as above described is covered with phenolic insulation molded in place. Each end of this shaft is drilled to receive the bearings Md. The shaft itself extends between the side plates 23 and 29. The bearings are brass cylinders inserted in holes in the side plates to Which their drilled flanges MI are secured by screws M2. a

When the screws M2 are removed and the two bearings at each end are withdrawn, the shaft and. the entire contact assembly may be removed from between the side plates provided of course that the flexible leads have been disconnected and also provided that the connection between 9 the link 3d and the arm 35 of the contact shaft are separated.

Assembly and operation of the contacts The contact arms d6 (see, for instance, Figure '7) are secured to the contact shaft by clamp members i which are held in place by a pair of screws at and 5? on each side of the shaft.

The outside poles are suitably positioned (Figure 17) by the contact arm caps or clamps 5m while the middle pole arm is held in position by the cap 5i. As is seen more particularly in Figure 3 the clamp or cap 5! is extendedto form the shaft actuating arm 35 and is drilled to receive pin 2i 2 in the upper end of the main toggle link A. movement of the operating mechanism 35 will raise or lower the pin 2 iii, therefore raising or lowering the shaft actuating arm 35 and so rotate the contact shaft 45 to move the contacts into and/or out of engagement.

As is more clearly. seen in Figures 2 and 17, secured to either or both ends of the steel contact iaft 65, is a steel arm 22!! and 22!. Each of these arms carries, as will be noted, two studs 223 and 224 which are riveted in place.

Secured to one of the studs of each of the members 22!) and 221 is a contact opening spring, the lower end of which may be attached to studs riveted to the insides of the bracket side plates. These two springs may bias the shaft towards opening position and assure quick opening.

The second of the studs, for instance stud 223 on the arm 2253, may be utilized to operate auxiliary switches or other devices by means, for instance, of the vertical insulated shaft 23!] attached to this stud and passing through the shelf of the bracket 30 (Fig. 2).

Thus, for instance, the vertical shaft 235] may operate auxiliary switch 236 in any suitable manner for any suitable purpose. The rotation of the contact shaft 35 towards opening position will through the arm 226 and the stud 223 force the vertical link 23c downwardly. The vertical link 235i is connected by pin 23l to the crank 232 on the shaft 233 of the switch 234. The downward motion of the vertical link 2% will result in rotation of the crank 232 and will therefore result in rOtatiOn of the shaft 233 and in the consequent operation of the various contacts and other portions of the switch suitably connected to and actuated by shaft 233.

Such switch 234 may be used where, for instance, the circuit breaker is to be connected with automatic reclosing circuits when it is open and such relay will obviously be reset to its original position when the solenoid or manual closing mechanism hereinafter described rotates the contact shaft it towards closing position thus raising the insulated link 23% and operating the switch.

As has been pointed out, preferably three contact arms l6 are mounted on this shaft, one for each pole of the circuit breaker as seen in Figure 2. On each side of each arm, there is cemented to the shaft insulation a Bakelite washer which improves the pole to pole and pole to ground insulation.

will be noted in Figure 2, the inter-pole washers are bevelled and flanged so that the bevelled and flanged portions M4 thereof are spaced apart so that an inter-phase barrier hi5 secured to the panel may extend between them. The cooperation of these parts makes it impossible for any flexible conductors of adjacent poles to be drawn together during heavy current flow 10 while at the same time any possibility of arcing over is obviated.

In the construction and arrangement of the contacts, the movable main contact is supported by an operating arm on the contact bar or shaft and is connected to the lower stud by a flexible shunt of suitable size.

Pressure on the main contact is obtained through the use of a compression type coil spring, mounted outside th current path, and, consequently, is unaffected by heating.

The pressure on the arcing contacts is also obtained by the same type of compression type coil spring protected from the arc.

The main contacts are protected by the sequence of operation in opening or closing of the device, since the main contacts close after the arcing contacts and open before them.

Although with the construction herein described, replacement of the contacts should not be necessary, the arrangement of the movable main contact lever and the movable arcing contact is such that access to both stationary and movable parts with a minimum amount of labor is possible.

As hereinafter described, accessibility of the main contacts is such that it is necessary only to remove one screw from the arc quencher assembly and lift it off manually so as to reach the contacts. In addition, as is hereinbefore described, the removal of the two bearings I40 of ing individual poles without opening others.

An important feature of the present invention is that the same structure may be used for single pole or multi-pole operation, that is, as seen for instance in the structure of Figure 2, the circuit breaker mechanism is so arranged that three poles are simultaneously operated by a single closing and tripping mechanism. The same type of structure may be so arranged as to take one, two or four poles or more.

In the actual operation of the contact assem-w blies herein described, when the contacts are fully closed and the latches are then tripped, the contact shaft 45 and the contact arm 45 rotate in a counterclockwise direction in the views of Figures 3 and 4. As the arm and the contact pivot pins 76 and 33 move away from the stationary contacts, the springs 69 and maintainthe moving contacts in engagement with the stationary contacts until in the rotation of the contact levers these levers l5 and GB strike their respective stops.

During this movement, the lower end 12 of the ag ressseen. ini'Figures 2; 3,4: and 5*- su-rrounding each pole is an arc chute I50 comprising; side plates? b5 i of fiber and supporting between them five shorter parallel: spaced:v plates? r52: also: of fiber! This are chute is more: fully described in Patent No. 2,338,715 and requires? no" further 'd'e-- scription here. I

Sufiici'ent inter p'h'ase barriersiare provided by the side plates [51' of'the are chute. However, additional inter-phase'barrier plates I145 (Figures 1-4 inclusive) maybe used'to make it impossible for: any'fiashing over of the arc from one pole to 13133 other; These inter-phase barriers are also fully described'in Patent No: 2,333,715 and require no further description here;

Various: other elements may, of course, be utilized connection with. and as an. integral part of the circuit breaker mechanism- Thus; for instance; as seen in Figure 2,: a suitable time delay element 950 may be provided. inconnection with: the overcurrent coil i H] to permit the breaker to carry normal" load above its trip setting for short periods of time. The specific details of the time delay elements are not herein discussed since they constitute no part or the:

present invention.

The various elements of the circuit breaker andv the operation of each 'of'the elements have been described in connectionwithv the descriptlon of the members thereof. Each of the in. dividual elements of the circuit breaker is inthe present invention integrated with each of the other elements to form a unified integral operative whole.

The rotation of the manual operating lever in onedirection causes the toggles to rise in the manner described, thus raising the link 34 rotating the arm 35-, rotating the contact shaft and closing the contacts.

The arcing contacts meet before the main con.- tactsare-in en-gagement with each other. Rotating the manual operating lever in the opposite direction trips the toggles in a manner hereinbefore' described, and causes the contacts to separate. the arcing contacts separating after the main contacts and the arc being establishedbetween the arcing contacts only.

The are immediately thereafter is transferred tothe arcing horns, and sweptup by the magnctic blow outinto the arc quencher 150.

The closing solenoid 530 may be utilized instead of the manual operating lever to close the-circuit breaker and automatic tripping may be substieration.

The arrangement of all of the parts of the aircuit breaker is such that assembly thereof is extremely simple. The entire arc quencher I50 including the arcing horn I60 maybe removed from the circuit breaker assembly by a single movement after the rotation of a single screw N52,

The entire movable contact assembly may-readily be disconnected from the remainder of the circuit breaker assembly by removing the beari2 ings H0; Figure 2, from the ends of'the contact shaft and removing the pin Zlil from its connectiOn between the arm 35 and the link 3% and pigtail.

And the entire togglemechanism assembly may be: readily removed for replacement and repair by means of the removal of screws 33'. A solenoid mechanism may readily be added to a hand operated breaker in the field.

The flexible. leads may be readily connected to the pigtail' post by means of the screws 98, and the pole pieces of the magnetic blow out coil are automatically connected in place when the arc quencher is mounted in place since these pole pieces are fastened to the sides of the arc quencher,

Assembly replacement and repair are thus greatly facilitated. ,Separation of the various parts for any purpose whatever is made easy and simple and the general arrangement of the members on the panel 23 facilitates the mounting of this" panel in a switch board with other similar circuit breakers or other switch devices.

The mounting of the movable contacts of the circuit breaker is such they may be readily removed for replacement and repair and the movable arcing contact tip which is subjected to the greatest erosion is further arranged so that the simple rotation or a screw 89 will permit the removal thereof and replacement.

In general, therefore, we have devised a circuit' breaker wherein the novelty lies not merely in the specific arrangement of the individual parts thereof, and not merely in the many extremely important novel constructions comprised therein, but also in the integration and arrangement of all of these parts so that they all operate as a single unit.

In the foregoing I have'described only those parts of the circuit breaker necessary to fully understand the operation of the movable contacts including the main movable contact and the movable arcingcontact. The various constructions herein described may be modified in many ways which will now be obvious to those skilled inthe art.

According'lmI prefer to be bound not by the specific description herein, but only by the appended claims.

I claim:

1. A movable contact structure for switching apparatus having a contact movable into and out of engagement witha complementary contact, said movable contact structure comprising a contact arm oscillable between 'two predetermined positions, a contact lever carrying said movable contact onone end thereof, a pivot pin, the back of said contact arm having a part-cylindrical depression and the front of said lever having a corresponding part-cylindrical depression, the two depressions when'in correspondence forming a cylindrical opening for receiving said pivot pin, means on said pin for preventing lateral movement thereof, and a spring member extending between said arm and lever at right angles to said pivot pin for maintaining the inside surface of said part-cylinder formed in said lever in abutting engagement with said pin and for maintaining the inside surface of said part-"cylinder formed in said arm in corresponding opposed abutting engagement with said pin, a first connection stud connected to said complementary contact, a second connection stud, a circuit connection from said second connection stud to the other end of said contact lever opposite from the end carrying said contact, the circuit path from said first to said second connection stud through said contacts and contact lever forming a loop, said circuit connection from said second stud including a pigtail connection extending substantially from the end of said lever in a direction to increase the effective length of said lever, the distance from said pivot point of said lever on said arm to the second connection stud being thereby greater than the distance from said pivot point to the engaging contacts to provide a blowon action of said contacts.

2. A movable contact structure for switching apparatus having a contact movable into and out of engagement with a complementary contact, said movable contact structure comprising a contact arm oscillable between two predetermined positions, a contact lever carrying a movable contact on one end thereof, a pivot pin, the back of said contact arm having a part-cylindrical depression and the front of said lever having a corresponding part-cylindrical depression, the two depressions when in correspondence forming a cylindrical opening for receiving said pivot pin, said pivot pin protruding beyond the side of said lever and having flanges at each side to prevent lateral movement thereof, and a spring member extending between said arm and lever at right angles to said pivot pin for maintaining the inside surface of said part-cylinder formed in said lever in abutting engagement with said pin and for maintaining the inside surface of said partcylinder formed in said arm in corresponding opposed abutting engagement with said pin, a first connection stud connected to said complementary contact, a second connection stud, a circuit connectionfrom said second connection stud to the other end of said contact lever opposite from the end carrying said contact, the circuit path from said first to said second connection stud through said contacts and contact lever forming a loop, the distance from said pivot point of said lever on said arm to the second connection stud being greater than the distance from said pivot point to the engaging contacts to provide a blow-on action of said contacts.

WILLIAM MAXWELL SCOTT, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,299,457 Gray Apr. 8, 1919 1,677,334 Getchell July 17, 1928 1,942,147 Merkel Jan. 2, 1934 2,025,386 Graves, Jr. Dec. 24, 1935 2,025,697 Baker Dec, 24, 1935 

